This invention relates to brick veneer/cavity wall construction and, more particularly, to a device used in association with a brick veneer/cavity wall system for insuring air circulation which inhibits mold growth.
Brick veneer/cavity walls are typically used in construction offering a brick facade or veneer to the structure. Brick veneer/cavity walls are made with inner and outer walls. The inner wall is typically constructed from wood or steel studs with an interior surface of drywall or the like. The outer face of the inner wall typically includes a layer of sheathing such as plywood, particle board or the like, that is nailed to a wood framed wall. Commonly, a vapor barrier covers the sheathing material to limit moisture from progressing through the inner wall. The outer wall is generally constructed of masonry materials that are held together by mortar.
Common practice in many municipal building codes requires a space of at least one inch forming a cavity between the inner and outer walls. The reason for this cavity is to provide a space for water to drain and air to circulate, thereby keeping the cavity dry. When the cavity is dry and air can circulate, the conditions for mold growth are minimized. Commonly, anchors span the spacing and are embed into the mortar securing the outer brick wall to the inner wall. Flashing of PVC, asphalt impregnated membrane or other materials are included on the lower portion of the inner wall and across the bottom of the cavity covering a portion of a foundation to underlay the outer wall.
Frequently during the construction of a building with a brick veneer/cavity wall, the required separation between the inner and outer walls is not provided either through inattention to detail, sloppy practices or the like. Even with an appropriate separation, often when the masonry wall is being constructed, the mortar and other debris can and does escape from the back face of the outer wall to contact the vapor barrier on the inner wall. Excess mortar that spans the cavity between the two walls is referred to as “bridging”.
One potentially catastrophic result of excess mortar bridging between the inner and outer walls is that the vapor barrier on the inner wall may be torn or damaged during construction thereby allowing moisture that travels along the “bridge” to become trapped between the remaining vapor barrier and the sheathing of the inner wall. Over time, such moisture conditions will generate mold growth which, if left unchecked would: attack the biodegradable structure and/or sheathing material causing them to fail, create a health hazard to occupants of the structure and/or present an expensive repair.
Mortar bridging from the outer masonry veneer to the attached structure is highly undesirable. Bridging provides a path for moisture, either condensed or liquid, to travel from the outer wall masonry work into the structure. Even if the vapor barrier is not breached, it may become saturated with moisture thereby providing a fertile environment for mold growth.